package com.newcoder.huawei;

import java.util.Scanner;

public class HJ55 {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别

        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int number = in.nextInt();
            int index = 1;
            int count = 0;
            while (index<number){
                if (String.valueOf(index).contains("7")){
                    count++;
                }

                if(index%7==0){
                    count++;
                }
                index++;
            }
            System.out.println(count);
        }
    }
}
